[Show abstract][Hide abstract] ABSTRACT: Bone ash, collagen, Ca and P composition, are considered themain factors affecting
mechanical properties in bones. However, a series of studies in bone and antler have shown
that some traceminerals, such as manganese, may play a role whose importance exceeds
what may be expected considering their low content. A previous study showed that a reduction
in manganese in antlers during a year of late winter frosts led to generalized antler breakage
in Spain, which included a reduction of 30%of cortical thickness, 27%reduction in
impact energy, and 10%reduction in work to peak force. Starting for this observation, we
experimentally studied the effects ofmanganese supplementation in adults and yearling
(yearlings) red deer under a balanced diet. Subjects were 29 deer of different age classes
(adult n = 19, yearlings n = 10) that were divided in a manganese injected group (n = 14) and
a control group (n = 15). Antler content in ashes and minerals, intrinsicmechanical properties
and cross section structure were examined at 4 points along the antler beam. A one way
ANOVA (mean per antler) showed that in yearlings, manganese supplementation only
increased its content and that of Fe. However, in adults, Mn supplementation increased the
mean content per antler of Ca, Na, P, B, Co, Cu, K, Mn, Ni, Se (while Si content was reduced),
and impact work but not Young’s modulus of elasticity, bending strength or work to peak
force. A GLM series on characteristics in the uppermost part examined in the antler, often
showing physiological exhaustion and depletion of body stores, showed also a 16%increase
in work to peak force in the antlers of the treated group. Thus, manganese supplementation
alteredmineral composition of antler and improved structure and some mechanical properties
despite animals having a balanced diet.
[Show abstract][Hide abstract] ABSTRACT: Ungulates select diets with high energy, protein, and sodium contents. However, it is scarcely known the influence of essential minerals other than Na in diet preferences. More-over, almost no information is available about the possible influence of toxic levels of essen-tial minerals on avoidance of certain plant species. The aim of this research was to test the relative importance of mineral content of plants in diet selection by red deer (Cervus elaphus) in an annual basis. We determined mineral, protein and ash content in 35 common Mediterranean plant species (the most common ones in the study area). These plant spe-cies were previously classified as preferred and non-preferred. We found that deer pre-ferred plants with low contents of Ca, Mg, K, P, S, Cu, Sr and Zn. The model obtained was greatly accurate identifying the preferred plant species (91.3% of correct assignments). After a detailed analysis of these minerals (considering deficiencies and toxicity levels both in preferred and non-preferred plants) we suggest that the avoidance of excessive sulphur in diet (i.e., selection for plants with low sulphur content) seems to override the maximization for other nutrients. Low sulphur content seems to be a forgotten factor with certain rele-vance for explaining diet selection in deer. Recent studies in livestock support this conclu-sion, which is highlighted here for the first time in diet selection by a wild large herbivore. Our results suggest that future studies should also take into account the toxicity levels of minerals as potential drivers of preferences.
[Show abstract][Hide abstract] ABSTRACT: Several theories predict a sex-biased investment either through unbalanced sex ratios in offspring or through differences in provisioning. According to them, one would expect an optimisation in indirect fitness, or else a compensation for increased mortality of one sex. In addition, biases in provisioning may also arise as a consequence of weight-dependent non-adaptive nutrient demands by offspring. This study examines milk provisioning and sex biases in offspring sex ratio together with maternal quality variables. Mothers of higher quality (weight and age) showed greater milk provisioning ability (in terms of production) resulting in greater calf weight gain. Mothers of sons produced greater yields of milk, milk protein, fat and lactose than mothers of daughters, and increased percentage of protein after controlling for higher male birth weight. In contrast, mothers of males did not differ from mothers of females in age or any body weight variables related to maternal quality. These results suggest that differences in milk production and composition for sons and daughters are rather a mechanism to optimise indirect fitness than a mechanism to compensate for increased mortality in male calves, or a consequence of greater weight-dependent nutrient demands by heavier male calves. Results also suggest that biases in milk provisioning may occur without biases in offspring sex ratio, and furthermore, in contrast to the prediction that biases should be relative to the mean investment of the population, that milk provisioning biases might not be relative.
No preview · Article · Dec 2004 · Behavioral Ecology and Sociobiology
[Show abstract][Hide abstract] ABSTRACT: Several theories predict offspring biases towards males or females with increasing reproductive resources of the mother to maximize reproductive returns by offspring, or as a result of prohibitive cost of the most expensive sex for young mothers or those in poor condition. This study examines foetus sex of 221 harvested hinds in a food-supplemented game estate for 10years, according to hind age class (yearlings, subadults or adults), precise age, body mass and condition, and jaw length. A logistic model showed that hinds had a greater probability of bearing a male foetus with increasing age class, but not with any other variable. The greatest bias was found in yearling hinds. After controlling for age class and mass, jaw length was smaller in pregnant compared to non-pregnant yearlings and subadults, which suggests a trade-off between reproduction and growth. The bias towards females in yearlings increased as gestation proceeded, which suggests that the bias might be a result of selective abortion of male foetuses. Although results do not exclude an investment in males to increase number of grand-offspring, they suggest that young hinds may produce daughters as a trade-off between low energetic-cost offspring and their need to grow.
No preview · Article · Jan 2004 · Behavioral Ecology and Sociobiology
[Show abstract][Hide abstract] ABSTRACT: This study estimates the caloric value of red deer milk as assessed relating bomb calorimetry data with the main milk nutrients. The study also examines milk energy estimates and lactation variables to compare Iberian red deer hinds (Cervus elaphus hispanicus) and the most studied Scottish red deer (C. e. scoticus). The final model predicted energy value (Ecal) in kcal/g of fresh milk from fat (F) and protein (P) content of milk, but not lactose: Ecal = 0.345 + 8.332 F + 5.403 P. Energy content per gram of milk increased with lactation stage but there was no difference between subspecies. However, subspecies differed in the daily and total energy production. Although milk energy values appeared to differ with estimates following the most used model developed from livestock, milk energy of deer estimated by both methods showed a very high correlation with each other, and both yielded also similar correlation coefficients with the remaining lactation variables. Calf gains showed a greater correlation with mean protein content and total protein yield, than with total energy yield or other milk nutrients. Milk protein appears to be more relevant to calf growth than gross energy yield.
No preview · Article · Jan 2004 · Journal of Experimental Zoology Part A Comparative Experimental Biology
[Show abstract][Hide abstract] ABSTRACT: Studies comparing lactation in wild mammals have shown that maternal weight scales with offspring weight, milk production, or its energy. However, no study appears to have scaled milk composition with maternal or offspring weight. Although diet affects milk composition and production, their effects in biological studies have almost never seemed to be controlled. In this study, we compare two subspecies of red deer, Scottish deer, Cervus elaphus scoticus (10 lactations), and Iberian deer, Cervus elaphus hispanicus (14 lactations), kept under the same diet and housing to assess differences in hind and calf weights and their trends, milk production and composition, and their allometric relationships. Scottish hinds were heavier, and calf weight and gains were greater than Iberian ones, with greater milk production and milk protein content, but they did not differ in fat or lactose content. Calf birth weight, milk production, and protein content showed significant allometric relationships with maternal weight, but no relationship was found for fat, lactose, or any of these variables with calf birth weight. Protein content correlated with calf birth weight, and calf weight trend depended on milk protein production rather than on that of fat or lactose. Protein may be the most important milk component to explain growth and milk composition differences between closely related mammals.
[Show abstract][Hide abstract] ABSTRACT: L. 2003: Lactation under food constraints in Iberian red deer Cervus elaphus hispanicus. -Wildl. Biol. 9: 131-139. The plane of nutrition in deer may affect body condition and lactation in hinds and calf growth both through long-term density-dependent effects and by short-term abiotically originated falls in food supply. Our study examines the effect of low nutrient availability after calving on lactation in captive Iberian red deer Cervus elaphus hispanicus. Twelve hinds and their calves were allotted to a food restricted (50-60% daily energy requirements) or a control group just after calv-ing. Hinds in the food-restricted group showed a greater body mass loss, pro-duced less milk and yield of milk fat, protein and lactose, and a different lac-tation curve shape, which resulted in reduced calf growth. However, the time course of lactation variables appeared to show a compensatory response up to week 4: a greater milk fat content in low-nutrition hinds than in the control group appeared to compensate for lower milk production, as neither calf nor hind mass differed from the control group, and lactation variables in both groups showed a standard lactation pattern. In contrast, as milk fat content fell below that of the control group after week 4, the low nutrition plane overcame a standard lac-tation pattern and groups differed in most variables (e.g. calf and hind mass and percentage of calf growth). Our results appear to show that deer mobilise body reserves in lactation to maintain offspring growth under temporary reductions in food intake, which may be a strategy of securing investment in current off-spring at the expense of reproducing the following season.
[Show abstract][Hide abstract] ABSTRACT: In deer, most of the earlier investigations on pineal function examined the effects of artificial photoperiods or the administration of melatonin to manipulate reproduction. However, endogenous melatonin rhythms have not been studied in red deer. Thus, we monitored seasonal changes in plasma melatonin concentrations in 16 adult female Iberian red deer living in outdoor enclosures. Blood was sampled on the day of each seasonal change every 3-4 hr overnight and 1 hr before and after sunset and sunrise. In addition, in six of the previous hinds, blood sampling during the hour prior and after sunset and sunrise was collected every 20 min. Significant differences were found both in amplitude and duration of the nocturnal plasma melatonin profiles in the four seasonal changes (P < 0.01). The nocturnal mean level of melatonin, the duration of nocturnal secretion levels and maximal concentrations were significantly higher at the winter solstice than in summer solstice or equinoxes (P < 0.05). Moreover, the mean overnight concentrations were significantly higher at the spring equinox and winter solstice than during the summer solstice and autumn equinox (P < 0.05). A pronounced elevation from low levels was recorded 1 hr after sunset, remained elevated during the hours of darkness and declined to low levels 1 hr after dawn. Concentrations close to sunrise were higher than those near sunset at all changes of season (P < 0.05). These results show for the first time in red deer that the pineal gland of the adult female is highly responsive to both daily and seasonal changes in natural environmental illumination, although overnight levels lasted longer than the photoperiodic night is all cases, particularly at the winter solstice.
Full-text · Article · Apr 2003 · Journal of Pineal Research
[Show abstract][Hide abstract] ABSTRACT: Nutrition may affect the balance between immunity and traits such as reproduction or growth. This study examines the effect of low nutrient availability on immunity indices and lactation in captive Iberian red deer. Twelve hinds and their calves were allotted to a food-restricted (50-60% daily energy requirements) or a control group just after calving. Low calorie intake exerted a greater effect on the immunity of calves than on that of hinds. Whereas no difference was found for hinds, calves of the low intake group showed mean immunoglobulin (Ig) levels higher than those on a standard diet, which suggests that Ig level may indicate the level of fighting against pathogens. Serum indices of body condition in calves showed generally positive correlations with milk nutrient production. In contrast, Ig level within each group showed a pattern inverse to that of the other group for early lactation: in the standard diet group, the greater the milk nutrient produced and calf growth, the lower the Ig level; this relationship was inversed in the low-nutrition group. These results suggest that, on a standard diet, high Ig levels may indicate high levels of pathogen fighting paired to poorer body condition. Inversely, once the first barriers of innate immunity are surpassed, only those calves on the low-nutrition group with greater resources would be able to spend more resources to fight infection. Thus, low calorie intake might boost its slowing effect on growth by increasing the costs of infection fighting.
No preview · Article · Dec 2002 · Biology of Reproduction